使用Hibernate_ID产生策略

id产生策略
increment 递增
identity  MySQL
   <id name="student_id" column="id">
    <generator class="identity"/>
sequence Oracle递增序列
   <id name="student_id" column="id">
    <generator class="sequence">
     <param name="sequence">person_seq</param>
    </generator>
   </id>
hilo  高低位
   <id name="student_id" column="id">
    <generator class="hilo">
     <param name="table">high_val</param>
     <param name="column">nextval</param>
     <param name="max_lo">5</param>
    </generator>
   </id>
seqhilo  使用序列的高低位
   <id name="student_id" column="id">
    <generator class="hilo">
     <param name="sequence">high_val_seq</param>
     <param name="max_lo">5</param>
    </generator>
   </id>
native  本地 hibernate-sequence递增表
   <id name="student_id" column="id">
    <generator class="native"/>
   </id>
assigned 程序设置
   <id name="student_id" column="id">
    <generator class="assigned"/>
   </id>
foreign  外部引用
   <id name="student_id" column="id">
    <generator  class="foreign">
               <param name="property">student</param>
       </generator>
      </id>